/** swap walkers using (low,high) ordered pairs
*
* The communication occur only between the (low,high) pairs.
* This does not guarantee a perfect balance swapWalkersBlocked and swapWalkersAsync
* try to achieve. However, the number of messages and their sizes are less than
* other methods.
*/
void GlobalWalkerControl::swapWalkersMap(MCWalkerConfiguration& W) {
NumSwaps++;
multimap<int,int> nw_map;
for(int i=0; i<NumContexts; i++) {
nw_map.insert(pair<int,int>(NumPerNode[i],i));
}
// multimap key is sorted with ascending order
multimap<int,int>::iterator it(nw_map.begin());
multimap<int,int>::reverse_iterator it_b(nw_map.end());
bool notpaired=true;
int target_context=-1;
int half=NumContexts/2;
int item=0;
bool minorcontext;
while(notpaired &&item<half) {
int i=(*it).second;
int j=(*it_b).second;
if(i == MyContext) {
target_context=j;
notpaired=false;
minorcontext=true;
} else if(j == MyContext) {
target_context= i;
notpaired=false;
minorcontext=false;
}
++it; ++it_b; ++item;
}
int nw_tot=NumPerNode[MyContext]+NumPerNode[target_context];
int nw_L=nw_tot/2;
int nw_R=nw_tot-nw_L;
int dnw(0);
if(minorcontext) {
dnw=nw_L-NumPerNode[MyContext];//how many to get
} else {
dnw=NumPerNode[MyContext]-nw_R;//how many to send
}
if(dnw) {//something to swap
if(minorcontext) {//open recv buffer
Walker_t& wRef(*W[0]);
OOMPI_Packed recvBuffer(dnw*wRef.byteSize(),OOMPI_COMM_WORLD);
OOMPI_COMM_WORLD[target_context].Recv(recvBuffer);
//create walkers
int last = W.getActiveWalkers();
while(dnw) {
Walker_t *awalker= new Walker_t(wRef);
awalker->getMessage(recvBuffer);
W.push_back(awalker);
--dnw; ++last;
}
} else {
Walker_t& wRef(*W[0]);
OOMPI_Packed sendBuffer(dnw*wRef.byteSize(),OOMPI_COMM_WORLD);
int last=W.getActiveWalkers()-1;
while(dnw) {
W[last]->putMessage(sendBuffer);
--dnw; --last;
}
OOMPI_COMM_WORLD[target_context].Send(sendBuffer);
//last=WalkerList.size()-1;
//while(dnw_save) {
// delete WalkerList[last];
// WalkerList.pop_back();
// --dnw_save; --last;
//}
//destroyWalkers(WalkerList.begin()+nsub[MyContext], WalkerList.end());
W.destroyWalkers(W.begin()+nw_R, W.end());
}
}
/* not used yet
struct lessNode {
inline bool operator()(const pair<int,int>& a,
const pair<int,int>& b) const {
return a.second < b.second;
}
};
//typedef pair<int,int> mytype;
//vector<mytype> id2n(NumContexts);
//for(int i=0; i<NumContexts; i++) {
// id2n=pair<int,int>(i,NumPerNode[i]);
//}
//
//std::sort(id2n.begin(),id2n.end(),lessNode);
*/
}
/** swap Walkers with Recv/Send
*
* The algorithm ensures that the load per node can differ only by one walker.
* The communication is one-dimensional.
*/
void WalkerControlMPI::swapWalkersSimple(MCWalkerConfiguration& W) {
NumSwaps++;
FairDivideLow(Cur_pop,NumContexts,FairOffSet);
vector<int> minus, plus;
int deltaN;
for(int ip=0; ip<NumContexts; ip++) {
int dn=NumPerNode[ip]-(FairOffSet[ip+1]-FairOffSet[ip]);
if(ip == MyContext) deltaN=dn;
if(dn>0) {
plus.insert(plus.end(),dn,ip);
} else if(dn<0){
minus.insert(minus.end(),-dn,ip);
}
}
Walker_t& wRef(*W[0]);
vector<Walker_t*> newW;
vector<Walker_t*> oldW;
#ifdef MCWALKERSET_MPI_DEBUG
char fname[128];
sprintf(fname,"test.%d",MyContext);
ofstream fout(fname, ios::app);
//fout << NumSwaps << " " << Cur_pop << " ";
//for(int ic=0; ic<NumContexts; ic++) fout << NumPerNode[ic] << " ";
//fout << " | ";
//for(int ic=0; ic<NumContexts; ic++) fout << FairOffSet[ic+1]-FairOffSet[ic] << " ";
//fout << " | ";
for(int ic=0; ic<plus.size(); ic++) {
fout << plus[ic] << " ";
}
fout << " | ";
for(int ic=0; ic<minus.size(); ic++) {
fout << minus[ic] << " ";
}
fout << endl;
#endif
int nswap=std::min(plus.size(), minus.size());
int last=W.getActiveWalkers()-1;
int nsend=0;
for(int ic=0; ic<nswap; ic++) {
if(plus[ic]==MyContext) {
//OOMPI_Packed sendBuffer(wRef.byteSize(),OOMPI_COMM_WORLD);
OOMPI_Packed sendBuffer(wRef.byteSize(),myComm->getComm());
W[last]->putMessage(sendBuffer);
//OOMPI_COMM_WORLD[minus[ic]].Send(sendBuffer);
myComm->getComm()[minus[ic]].Send(sendBuffer);
--last; ++nsend;
}
if(minus[ic]==MyContext) {
//OOMPI_Packed recvBuffer(wRef.byteSize(),OOMPI_COMM_WORLD);
OOMPI_Packed recvBuffer(wRef.byteSize(),myComm->getComm());
//OOMPI_COMM_WORLD[plus[ic]].Recv(recvBuffer);
myComm->getComm()[plus[ic]].Recv(recvBuffer);
Walker_t *awalker= new Walker_t(wRef);
awalker->getMessage(recvBuffer);
newW.push_back(awalker);
}
}
if(nsend) {
nsend=NumPerNode[MyContext]-nsend;
W.destroyWalkers(W.begin()+nsend, W.end());
}
//add walkers from other node
if(newW.size()) W.insert(W.end(),newW.begin(),newW.end());
}
